/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package io.github.ramerf.wind.core.io;

import io.github.ramerf.wind.core.reflect.ReflectionUtils;
import io.github.ramerf.wind.core.util.BeanUtils;
import java.io.*;
import java.lang.reflect.*;
import java.net.URI;
import java.net.URL;
import javax.annotation.Nullable;

/**
 * Utility for detecting and accessing JBoss VFS in the classpath.
 *
 * <p>As of Spring 4.0, this class supports VFS 3.x on JBoss AS 6+ (package {@code org.jboss.vfs})
 * and is in particular compatible with JBoss AS 7 and WildFly 8+.
 *
 * <p>Thanks go to Marius Bogoevici for the initial patch. <b>Note:</b> This is an internal class
 * and should not be used outside the framework.
 *
 * @author Costin Leau
 * @author Juergen Hoeller
 * @since 3.0.3
 */
public abstract class VfsUtils {

  private static final String VFS3_PKG = "org.jboss.vfs.";
  private static final String VFS_NAME = "VFS";

  private static final Method VFS_METHOD_GET_ROOT_URL;
  private static final Method VFS_METHOD_GET_ROOT_URI;

  private static final Method VIRTUAL_FILE_METHOD_EXISTS;
  private static final Method VIRTUAL_FILE_METHOD_GET_INPUT_STREAM;
  private static final Method VIRTUAL_FILE_METHOD_GET_SIZE;
  private static final Method VIRTUAL_FILE_METHOD_GET_LAST_MODIFIED;
  private static final Method VIRTUAL_FILE_METHOD_TO_URL;
  private static final Method VIRTUAL_FILE_METHOD_TO_URI;
  private static final Method VIRTUAL_FILE_METHOD_GET_NAME;
  private static final Method VIRTUAL_FILE_METHOD_GET_PATH_NAME;
  private static final Method VIRTUAL_FILE_METHOD_GET_PHYSICAL_FILE;
  private static final Method VIRTUAL_FILE_METHOD_GET_CHILD;

  protected static final Class<?> VIRTUAL_FILE_VISITOR_INTERFACE;
  protected static final Method VIRTUAL_FILE_METHOD_VISIT;

  private static final Field VISITOR_ATTRIBUTES_FIELD_RECURSE;

  static {
    ClassLoader loader = VfsUtils.class.getClassLoader();
    try {
      Class<?> vfsClass = loader.loadClass(VFS3_PKG + VFS_NAME);
      VFS_METHOD_GET_ROOT_URL = vfsClass.getMethod("getChild", URL.class);
      VFS_METHOD_GET_ROOT_URI = vfsClass.getMethod("getChild", URI.class);

      Class<?> virtualFile = loader.loadClass(VFS3_PKG + "VirtualFile");
      VIRTUAL_FILE_METHOD_EXISTS = virtualFile.getMethod("exists");
      VIRTUAL_FILE_METHOD_GET_INPUT_STREAM = virtualFile.getMethod("openStream");
      VIRTUAL_FILE_METHOD_GET_SIZE = virtualFile.getMethod("getSize");
      VIRTUAL_FILE_METHOD_GET_LAST_MODIFIED = virtualFile.getMethod("getLastModified");
      VIRTUAL_FILE_METHOD_TO_URI = virtualFile.getMethod("toURI");
      VIRTUAL_FILE_METHOD_TO_URL = virtualFile.getMethod("toURL");
      VIRTUAL_FILE_METHOD_GET_NAME = virtualFile.getMethod("getName");
      VIRTUAL_FILE_METHOD_GET_PATH_NAME = virtualFile.getMethod("getPathName");
      VIRTUAL_FILE_METHOD_GET_PHYSICAL_FILE = virtualFile.getMethod("getPhysicalFile");
      VIRTUAL_FILE_METHOD_GET_CHILD = virtualFile.getMethod("getChild", String.class);

      VIRTUAL_FILE_VISITOR_INTERFACE = loader.loadClass(VFS3_PKG + "VirtualFileVisitor");
      VIRTUAL_FILE_METHOD_VISIT = virtualFile.getMethod("visit", VIRTUAL_FILE_VISITOR_INTERFACE);

      Class<?> visitorAttributesClass = loader.loadClass(VFS3_PKG + "VisitorAttributes");
      VISITOR_ATTRIBUTES_FIELD_RECURSE = visitorAttributesClass.getField("RECURSE");
    } catch (Throwable ex) {
      throw new IllegalStateException("Could not detect JBoss VFS infrastructure", ex);
    }
  }

  protected static Object invokeVfsMethod(Method method, @Nullable Object target, Object... args)
      throws IOException {
    try {
      return method.invoke(target, args);
    } catch (InvocationTargetException ex) {
      Throwable targetEx = ex.getTargetException();
      if (targetEx instanceof IOException) {
        throw (IOException) targetEx;
      }
      ReflectionUtils.handleInvocationTargetException(ex);
    } catch (Exception ex) {
      ReflectionUtils.handleReflectionException(ex);
    }

    throw new IllegalStateException("Invalid code path reached");
  }

  static boolean exists(Object vfsResource) {
    try {
      return (Boolean) invokeVfsMethod(VIRTUAL_FILE_METHOD_EXISTS, vfsResource);
    } catch (IOException ex) {
      return false;
    }
  }

  static boolean isReadable(Object vfsResource) {
    try {
      return (Long) invokeVfsMethod(VIRTUAL_FILE_METHOD_GET_SIZE, vfsResource) > 0;
    } catch (IOException ex) {
      return false;
    }
  }

  static long getSize(Object vfsResource) throws IOException {
    return (Long) invokeVfsMethod(VIRTUAL_FILE_METHOD_GET_SIZE, vfsResource);
  }

  static long getLastModified(Object vfsResource) throws IOException {
    return (Long) invokeVfsMethod(VIRTUAL_FILE_METHOD_GET_LAST_MODIFIED, vfsResource);
  }

  static InputStream getInputStream(Object vfsResource) throws IOException {
    return (InputStream) invokeVfsMethod(VIRTUAL_FILE_METHOD_GET_INPUT_STREAM, vfsResource);
  }

  static URL getURL(Object vfsResource) throws IOException {
    return (URL) invokeVfsMethod(VIRTUAL_FILE_METHOD_TO_URL, vfsResource);
  }

  static URI getURI(Object vfsResource) throws IOException {
    return (URI) invokeVfsMethod(VIRTUAL_FILE_METHOD_TO_URI, vfsResource);
  }

  static String getName(Object vfsResource) {
    try {
      return (String) invokeVfsMethod(VIRTUAL_FILE_METHOD_GET_NAME, vfsResource);
    } catch (IOException ex) {
      throw new IllegalStateException("Cannot get resource name", ex);
    }
  }

  static Object getRelative(URL url) throws IOException {
    return invokeVfsMethod(VFS_METHOD_GET_ROOT_URL, null, url);
  }

  static Object getChild(Object vfsResource, String path) throws IOException {
    return invokeVfsMethod(VIRTUAL_FILE_METHOD_GET_CHILD, vfsResource, path);
  }

  static File getFile(Object vfsResource) throws IOException {
    return (File) invokeVfsMethod(VIRTUAL_FILE_METHOD_GET_PHYSICAL_FILE, vfsResource);
  }

  static Object getRoot(URI url) throws IOException {
    return invokeVfsMethod(VFS_METHOD_GET_ROOT_URI, null, url);
  }

  // protected methods used by the support sub-package

  protected static Object getRoot(URL url) throws IOException {
    return invokeVfsMethod(VFS_METHOD_GET_ROOT_URL, null, url);
  }

  @Nullable
  protected static Object doGetVisitorAttributes() {
    return BeanUtils.getFieldValue(null, VISITOR_ATTRIBUTES_FIELD_RECURSE);
  }

  @Nullable
  protected static String doGetPath(Object resource) {
    return (String) BeanUtils.invokeMethod(resource, VIRTUAL_FILE_METHOD_GET_PATH_NAME);
  }
}
